Energy requirements in megaprojects

The following paragraphs will bring light on a very important and little discussed topic, which often becomes a risk for the project delivery deadline and has a decisive influence on the operating costs.

Metros, tramways and railroads need energy to be able to transport passengers back and forth. The energy is in the form of electricity and is collected at various points in the transport network. These collection points are called electrical connections, and it is their sizing that we are going to discuss.

Deciding how much energy a tramway or a new metro extension, for example, needs is a commitment that no one wants to face without providing a major factor, since after implementing the infrastructure, the ridicule of not having enough energy will always be greater than that of having too much. In extensions it is usually the system operator who defines the energy needs, if the operator has been in place for a long time, he will have real data on which to base his calculations, and by his own means or through technical assistance he will be able to analyze them to know the needs. In new networks, without data, calculations are usually made with large numbers, which will then be increased and rounded and after passing from table to table will end up giving a value far removed from that required in the first years of operation.

At this point I would like to make an example about the Spanish regulations that define extension rights. Although each country may have specific regulations in this regard, they will not differ greatly from what is written here. The Spanish Royal Decree 1048/2013, in its article 25 tells us that for installations that require more than 250 kW in high voltage, the cost of the new extension facilities to meet the new supply will be paid for the applicant. In other words, depending on the power required, the distribution company will define which installations and equipment are necessary, and the developer will have to implement and transfer them. And it is here when two of the most important risks arise in the projects, missed deadlines and cost overruns. In my experience, I have found that negotiations with distribution companies are often long and tedious. These companies have their own interests, and can delay negotiations for months or even years, which can leave the project in “electrical limbo”. It is at these times that institutional support is needed to be able to approach such talks successfully. Technically, I can only think of one way to speed up these procedures, and that is to request the necessary power in the short/medium term, and now I will tell you why.

Article 28 of the Spanish Royal Decree 1048/2013 defines the validity of the extension rights, "In the event that the user contracts a power lower than the power linked to the extension rights ... they will maintain their validity for a period of three years for low voltage and five years for high voltage". So, in my opinion, we find ourselves in one of the classic errors in the definition of electricity needs, and that is that the calculation is usually made in the long term. For example, the developer of a new transport network, after rounding off his energy needs, puts on the table that he needs 10 MW and a redundant connection for another 10 MW. The business is served for the power distribution company, since such amounts result in millionaire investments for its installations. After starting to operate, the operator does not contract those 20 MW because they involve the payment of access rights, which are priced according to the kW to be contracted (19.70 €/kW) and are paid once, and involve exponentially increasing the power term of the electricity bill, since this term is a function of the contracted power. Therefore, the operator evaluates its real needs and significantly reduces the contracted power up to 4 MW. After 5 years, no increase in contracted power has been required and the rights of up to 16 MW are lost, passing directly to other consumers. If the short/medium term needs had been put on the table at the beginning, accompanied by a realistic study, the investments for this concept would have been much lower, the negotiations with the distribution company less time consuming and, in case a long term power increase was required, it could have been planned at a later stage.

On the other hand, long-term energy needs are required to calculate the internal distribution facilities, such as protections, cables and transformers. Too high energy needs translate into the purchase of transformers that will work in low power ranges or, in other words, with low efficiency and high load losses and, if there are redundant transformers, high no-load losses. To put numbers, poorly optimized installations can have energy losses in the order of 20-30% of total consumption.

As a conclusion and according to my experience, the calculation of the electrical needs is done in the long term, defining the electrical needs for the mature phase of the project, which can be useful to calculate the internal distribution electrical installations, but it is not the most appropriate method to define the power needs to negotiate with the power distribution company. A good consumption analysis can optimize the installation, reduce consumption and help the management of the new supply points to reach a successful conclusion more quickly, let's say with less voltage.